Electrical organ



June 2,5, 1968 w. c. WAYNE. JR

' ELECTRICAL oRGAN ATTORNEYS.

June 25, 1968 LEc'rRIcAL oRGAN 3 Sheets-Sheet 2 Filed Aug. l, 1960 ATTOCNEYI.

United States Patent O 3,390,223 ELECTRICAL 'ORGAN William C. Wayne, Jr., South Fort Mitchell, Ky., assigner to D. H. Baldwin Company, a corporation of Ohio Filed Aug. 1, 1960, Ser. No. 46,704

25 Claims. (Cl. 84-1.24) t Musical keyboard instruments of the type in which tones are generated by electrical means are variously modified as to timbre (hereinafter referred to synonymously as voice, tone color or tone quality), and are reproduced through output systems generally comprising ampliers and loudspeakers, have come into Widespread use. Means for generating tones have included electrical oscillators, reeds, magnetic tone wheels and others. In an exemplary instrument, tones of complex wave form are generated .by electrical oscillators, are collected in various headers by means of switches actuated by playing keys, are modified as to harmonic content by formant-type filter circuits, and are then reproduced. United States Patent No. 2,233,948 issued Mar. 4, 1941 in the name of Kock shows an instrument of this type.

In another type of instrument, tones of simple or sinusoidal wave form are generated usually 'by electromechanical means, and are mixed in such a way and in such amplitudes as to meet the requirements of particular timbres or voices, and are then reproduced.

All such instruments are inadequate for ecclesiastical use in that they do not imitate perfectly the tones produced by the pipes of a pipe organ, but produce relatively simpler tones which are readily distinguishable there` from, and for concert and church use are not as pleasing to the ear. For one thing, in a pipe organ, various ranks of pipes are frequently caused to speaktogether. Since these ranks are in practice slightly detuned from each other, ensemble effects result. The effects are similar to those obtained when a plurality of violins are playing the same note as distinguished from a single violin. Also, in the pipe organ, certain ranks of pipes are deliberately detuned from other ranks by greater amounts so that when these ranks are played together, musically rich effects are obtained, generally designated by the term celeste .It has hitherto been suggested that the ranks of generators in electrical musical instruments be multiplied, with greater or lesser amounts of detuning as between the ranks, so that ensemble andy celeste effects could be obtained. This is effective for the specific purpose; but it is expensive, and' inasmuch as it does not solve the Whole problem, there are instances in which it may be questionable whether the additional expense is justified for the result gained.

Organ pipes have other specific tone `characteristics which have not hitherto been imitated by electrical means. The tone envelope characteristics of the sounds produced by organ pipes are distinctive. Not only is the onset of the tones gradual; the tones do not cease abruptly, but die away in accordance with an exponential curve.- It has not been found practicable for a musician to duplicate these characteristics by the use of gradually acting or resistive switches in connection with the keys. Moreover, when some organ pipes are actuated, the first tone heard is the second harmonic or some other partial or subharmonic of the tone combination, after which the fundamental and other Apartials are added to the tone. The onset and decay rates of reed tones are much more rapid than those of diapason and flute tones. Yet again, when air is cut olf from an organ pipe, and during the exponential decay of the tone (which results from the pipes resonator remaining in active condition for a brief interval), there is a change in the timbre or the frequency or both from that existing in the steady state. Thus many organ pipes go iCC slightly hat when they are deactivated and before the sound ceases to be audible. There are types of pipes, designated Harmonic Flute or Harmonic Trumpet for example, which are so constructed that when they are actuated by a blast of air, there will be an audible effect of a frequency which is half of the fundamental frequency of the pipe, and which will -be somewhat audible throughout the operation of the pipe, but more so at the start and finish of its operation.

The operation of organ pipes is usually accompanied by a certain amount of wind noise which may be apparent at the start of the actuation and before the tone comes on, or which may .be apparent throughout the operation of the pipe.

It is a primary object of the. invention to provide an electrical musical instrument of the organ type capable of producing tones having any or all of the above noted characteristics at a cost which will stillbe substantially below the cost of a comparable pipe organ.

The invention will be described in connection with a concert organ having Great, Swell, Choir and Echo manual divisions, and a Pedal division, it being understood that the principles of the invention are applicable to organs of lesser or greater elaboration.

It is an object of the invention to provide a system in which simple make-and-break switches may be used for both the keying of audio frequency voltages of complex wave form and for the selection oftone colors.

It is an object of the invention to provide a system in which harmonics or partials are individually selectable and adjustable by the organ voicer as to amplitude and, if desired, as to wave form, change with time, often referred to as sonancef It is an object of the invention to provide a system using resonators which may have exact harmonic or stretched harmonic relationship to the fundamental frequencies, the latter condition simulating actual acoustically loaded pipes whose effective length changes because the end-correction is a function of frequency.

It is an object of the invention to provide a system in Which ensemble and celeste effects may be obtained with minimum complication and cost in a concert organ.

It is an object of the invention to provide a system in which initial transient amplitude and frequency modulations may be automatically obtained and in which nal transients, similar to those which occur because of the decrease in air pressure in an organ pipe when the valve is closed, are also obtainable. v

It is an object of the invention to provide means whereby the pulse-like oscillations from a source may be randomly frequencyemodulated by a noise frequency, or periodically modulated by a sub-audio frequency, as in a vibrato, or both. Yet again, it is an object of the invention to provide for the linear addition of noise frequencies to the pulse voltage to produce random amplitude fluctuations similar in effect to the windiness in organ pipes.

It is an object of the invention to provide a system in which at the onset of a tone some partial other than the fundamental may be caused to sound first. v

The term parta as used herein, as a noun, applies to a particular frequency component of a complex wave, which may be, but is not necessarily, harmonically related to the fundamental frequency of the wave. The term, in the broad sense, is inclusive of the fundamental, or even a sub-harmonic frequency.

As used herein, the Word system signifies an organization of electrical or mediano-electrical parts coacting to produce the results of the invention.

The above noted and other objects of the invention which are hereinafter set forth or will be apparent to one skilled in the art upon reading these specifications are accomplished by lthat construction and arrangement of parts of which certain embodiments will now be described. Reference is made to the accompanying drawings wherein: FIG. 1 is a diagrammatic showing of the system of the invention.

FIG. 2 is a partial circuit diagram showing the relationship of a generator and a serie-s of resonators.

FIG. 3 is a partial circuit diagram showing the obtaining of different transients from a single generator output by the use of different resonators.

vFIGS. 4 and 5 are oscillograph representations of the transients obtained in FIG. 3.

FIG. 6 is a partial circuit diagram illustrating connections between the con-sole and the remote cabinet.

The invention will be described in connection with the use of ranks of generators of the type shown in the Kock patent hereinabove referred to and in Patent No. 2,555,038 dated May 29, 1951, to Jones, or preferably of the unsymmetrical multi-vibrator type described in Reference Data for Radio Engineers, third edition, 1949 Federal Telephone and Radio Corporation, page 268, it being understood that the invention is not confined thereto. Any sources of electrical oscillations capable of producing wave forms which are related in fundamental frequency in accordance with the tempered musical scale, and which produce oscillations rich in harmonic content, may be used. Each exemplary generator rank is organized in twelve cascaded series, each embodying a stable oscillator producing frequencies in a high register, and a series of controlled oscillators operating at 1/2, 1A, etc. of the frequency of the controlling oscillator. Such a generator rank is easily organized on a single frame (there being a chassis for each series, and usually a power chassis), the generator rank being fairly compact and easily mounted.

It may be stated at the outset that a'plurality of generator ranks are used in the ysystem of this invention to obtain ensemble and celeste effects and for other purposes. In FIG` 1 the generator ranks are shown in the upper lefthand corner as blocks. Numerals 1 to 9 inclusive are generator ranks of standard type producing harmonically rich oscillations extending from about 32 c.p.s. (C1) to 4 kc. (C8). Two of these generator ranks are detuned with respect to each other or to the others by an amount-suiiicient to give a celeste effect (usually from 12 at to 8 sharp, where the symbol e stands for cent(s), which is one/one-hundredth of a semi-tone in the equally-tempered scale) while the remaining seven are detuned as respects each other only by amounts (generally 3 flat to 3 sharp) sutcient to produce an ensemble effect. Needless to say, one of the generator ranks will usually be tuned accurately on pitch, referred to the A 440 c.p.s. standard. The number of generator ranks is to a considerable extent arbitrary, fewer or more may be used depending upon the elaboration of the instrument and the number of voices planned. Numerals 10 and 11 indicate supplementary generator ranks producing oscillations from 4 kc. (C8) to 8 kc. (C9). There are two of these so that they may be detuned with respect to each other, for ensemble. Numeral 12 indicates another small generator rank producing oscillations from 8 kc. (C9) to 16 kc. (C10). Since such high frequencies approach tihe limit of audibility, ensemble is not too important, and only one such rank need be provided. Numeral 13 indicates another small supplementary generator rank producing oscillations from 16 c.p.s. (C0) to 32 c.p.s. (B0), largely for pedal use. Ensemble is not too important here either for the same reasons.

As indicated, any sort of generator may be used, including electronic, electro-mechanical, photo-electric and others. Electronic generators may be transistorized to diminish bulk. Nevertheless, considering the bulk of the generator ranks, the bulk of the resonators hereinafter described, and the complexity of the interconnections, it will not usually be found feasible to house all of the electrical parts of the system in a console. Consequently it is contemplated that the bulk of the electrical parts making up the system will be locatedAin a cabinet (configured to give ready access to the parts for replacement and repair) at a point remote from the console. The cabinet may, for example, be located in an organ loft, or even in a basement or other separate part of a building in which the organ is to be used.

The dot-dash rectangle 14 in FIG. 1 represents an organ console. It may contain manuals, 15, 16, 17 and 18 for the Swell, Great, Choir and Echo organs and a Pedal clavier 19, together with simple make-and-break switches for each key. In an instrument having 61 keys per manual and 32 in the pedal clavier, this part of the console would be connected with the remote cabinet by a 276 wire cable, marked 125, for DC control currents. The console will also contain stop tabs with switches for the several voices pertaining to the manuals and pedals. Assuming 13 voices for the Swell, 9 voices for the Great, 11 voices for-the Choir, 8 voices for the Echo and 15 voices for the Pedal claiver, this part of the console would be conected with the remote cabinet by a 56 wire cable 126. A common return path for these control circuits must also be provided. The stop assemblies are indicated diagrammatically at 20, 21, 22, 23 and 24. Combination piston will probably be desired. If these are arranged forl by mechanical means in the console, the wiring is not complicated. If of the electrical remote capture variety, it is obvious that additional cables must be employed. The console will also contain expression pedals. Certain ones of these are indicated at 25, 26 and 27 for the Swell, Choir and Echo divisions, it being understood that more or fewer may be provided as desired. These will be required to be connected to other components of the system by suitable wiring, The console may contain other control elements in accordance with the designers desires.

Where herein data are given as to numbers of manuals, numbers of voices, numbers of circuit connections and the like, it will be understood that these are exemplary but not limiting. The data herein chosen are appropriate for a concert organ of the American Classic style, as an example.

The connections carrying audio frequency voltages from the several generators in the ranks 1 to 13 are brought out most conveniently to a central terminal board 28 located in the cabinet. In the exemplary embodiment, there will be a total of 813 connections to and a minimum of this number from this board. Oscillations from V the generators are next carried to a gang of remote key switches indicated at 29 in FIG. 1 and divided into blocks indicative of switches for the Swell, Great, Choir and Echo manuals and the Pedal clavier. In the system of this invention, oscillations of different footages are not collected in separate headers, but must be handled individually. At the same time, it will be found that it is desirable, upon the actuation of a single key, to derive oscillations from a plurality of generators. As a consequence, the remote key switches in the bank 29 are generally in the form of electro-magnetically actuated multi-contact relays, or their equivalent. By way of example, there may be 3,497 connections between the remote key switches in the bank 29 and the remote tone color switches in the bank 30. Here again, each lead containing oscillations derived from a generator must be switched separately; and the tone color switches are also in the form of multi-contact relays. There will be at least the same number of connections (namely 3,497) between the bank of remote tone color switches 30 and a spreader terminal board 31 to facilitate connections to individual resonator circuits as hereinafter described. Key and stop switching details (FIG. 6) will be described later.

Before describing the remainder of the system as illustrated in FIG. 1, it is necessary to describe the manner in which any given voice is derived from a single set of oscillations, Reference is made to FIG. 2 wherein the block 32 is representative of a single pulse 'source or generator. As previously indicated, the generator may take various forms, but is preferably a relaxation oscillator or controlled oscillator.

The generator 32 may be fed with the required bias voltage providing a voltage sensitive frequency control means 33. Ahead of this means there is shown a potentiometer 34 for average tuning, connected between ground and a suitable souce of B+ voltage such as one capable of delivering 300 volts. f

There is shown in connection with the yinput lead 35 of the means 33 an oscillator 36 arranged to operate at a. subaudible frequency such as 7 cycles per second. This oscillator is used to provide a frequency modulation or vibrato for the output of the generator 32. It may be provided with a potentiometer 37 to control the extent of vibrator and a switch 38.

'The block 39 in FIG. 2 represents an electrical noise generator, usually a circuit containing a gaseous tube of the thyratron variety. The output of this noise generator is divided. By means of a lead 40, a portion of the output is carried back to the lead 35 through a potentiometer 41 and switch 42. The introduction of noise frequency into the generator 32 will produce a frequency variation which is not similar to a vibrato but rather gives an effect bordering on ensemble. Suitable decoupling resistors 127 and 128 are provided so that potentiometers 37\and 41 can be adjusted without interaction. The other portion of the output of the noise source 39 is carried througha potentiometer 43 to the resonator circuits herinafter described. The output of the generator 32 is similarly carried through a pulse amplitude potentiometer 130 to the resonator circuits later described. The combined outputs of the generator 32 and the noise source 39 may be so transferred through a linear mixer indicated at 4S.

The purpose of the resonator circuits is to break up the complex tone derived primarily from the generator 32 into suitable partials which may be later combined at desired amplitudes toproduce a given voice. The operation, however, is not similar to ,the combination of harmonically related sine-wave oscillations for voicing purposes, since the partials produced -by the resonant circuits offthis invention are not strictly steady-state sinewave in character and for that reason, and because of the mode of operation of the resonant circuits, the resultant voice has various characteristics including an initial` transient, a tone envelope similar to that of a pipe organ, a similar final transient, and the like.

The resonator circuits, in order to fulfill their function, must have a relatively high'Q, where Q is defined as 21- times the ratio lof vibrational energy stored in the circuit to the energy lost per cycle at a given frequency. A number of types' of resonators may be employed including active L-C Q-multiplers -(e.g. Colpitts oscillators on the verge of oscillation), active R-C resonators (phase Y shift oscillators on the verge of oscillation), and passive L-C resonators (resonant tank circuits) using high Q toroidal inductors which have stable inductance'values with varying AC levels, have good immunityto magnetically coupled cross-talk andjyield high values of inductance and Q for their physical volume because of their magnetically efiicient configuration. Since electrical resonators are used to affect the transients and other characteristics of electrical oscillations in the way described above, it will be understood in thesespecifications and in the claims which follow that the termelcctrical resonators is used in a sense broad enough to include electrical circuits for the purpose, irrespective of whether they contain purely electrical means for sharpening the response to a particular frequency orA whether they include mechanical means for that purpose, such as tuned reeds or other vibratile devices or acoustic resonators. Electrical resonators such as will serve the purpose of this invention are well known in the art.

' A particular type of resonator circuit is shown in FIG.

2 in the dashed rectangle 46. The first element is an electronic amplifier indicated generally at 47. The resonator proper is an active L-C resonator which comprises an inductance 48- and capacitors 49 and 50 together with an electronic tube4 51. This constitutes a Colpitts-oscillator type of resonant circuit. The gain of the electronic tube 51 greatly increases the effective Q of the circuit. The output may be provided through a linear mixing resistor 52 for combination with the remaining eight resonator outputs at header 71. The amplitude of the partial passed by resonator 46 is controlled by a resistor 53 or other suitable impedance. The feeding of the outputs combined collected at point l4S to the resonator 46 is controlled by :a key switch 54, which will be one of the remote key switches of the bank 29 of FIG. 1, in series with one pole of multi-contact tone color switch 131.

Other resonator circuits are indicated in FIG. 2 by the blocks 55 to 62 inclusive. These may be regarded as resonatorsfpassing other partials of the applied signal voltage, and with respect to each of these, there will be a controlling resistor 63 to 70 to determine the amplitude of the particular partial. The outputs of theA several resonator circuits are collected in a header 71 for transmission to an amplifier and loudspeaker (not shown).

It is characteristic of resonator circuits of the various types set forth above that there is a finite build-up time for an abruptly applied signal so that the transmitted signal or portion thereof comes on gradually, which is musically desirable. Therefore, the key switch 54 (and other key switches) can be of the simple make-break type. Furthermore, there is a finite resonator decay time so that an effect of reverberation is secured in the output system, if Qvalues are chosen proportional to input signal frequencies. A certain amount of the noise frequency from the source 39 will pass through the several resonator circuits, thus giving the effect of tuned windiness common in organ pipes.

One aspect of the operation of high Q Yresonators is illustrated in FIGS. 3, 4 and 5. Here the output ofa single generator 114 is divided into paths 115 and 116, each path having a switch 117 or 118 which are part of a relay switch as set forth above. The paths each have separately operated tone color switches 119 and 120, with associated amplitude-adjusting impedances 53a and 53b. The paths are shown joining beyond these switches and connected to an output system 121.

Path contains a high Q resonator 122. Assuming the fundamental frequency generated at 114 to be 440 c.p.s., the resonator 122 may be tuned to 439 c.p.s. This will give an initial transient envelope to the transmitted signal appearing on line 71a similar to that shown at 123 in FIG. 4. The effect of resonator 122 will be to give an initial transient amplitude modulation to the transmitted signal of a rate equal to the difference between the frequency of the input signal and the frequency of peak response of the resonator, namely, one c.p.s. in this example. The `duration of this effect is proportional to the magnitude of the resonator Q. Branch circuit 116 is shown as containing a resonator 124 which is tuned to 437 c.p.s. Initial transients produced by this resonator are illustrated at 129 in FIG. 5, and the effect is audibly different from that illustrated in FIG. 4. This illustrates that two different resonators connected to the output of the same -generator may produce tones which, although they are similar in the steady state, nevertheless produce entirely different initial transients.

As hereinafter described, a plurality of resonators may be used in connection with the complex output of any generator.

It will be understood that the particular voice obtained from oscillations originally -derived from -the source 32 in FIG. 2 will be dependent upon the -value of the re` sistors 53 and 63 to 70, as determining the amplitude of the various partials. Other voices can be obtained from the same original oscillations by providing other key-switched and tone-color-switched connections between the source 32 and the sarne resonator circuits but using different values in these circuits for the resistors corresponding to 53 and 63 to 70. The number of resonator circuits connected to a-ny given source of oscillations may be Varied as desired depending upon the range of partials desired in the particular voice, nine-resonators being shown in use in FIG. 2. i y

Moreover, different oscillators may be connected to the same resonators, for it will be evident that if the resonator 46 passes the fundamental of, say, C4 and the resonator 55 passes the second harmonic thereof, the resonator 55 may also serve as the fundamental resonator circuit for C an octave higher, and so on. -An exemplary set of components for accomplishing this is illustrated by the generator source 32', amplitude control 130', key switch 54', tone-color switch 131 and resistor 53. It will be understood that connections from vibrato oscillator 36 and noise source 39 will be made in a Amanner similar to that for pulse source 32. Indeed, while more than one bank'of resonators may be used for each division of the organ, it is possible to use a single bank of resonators to handle the entire output of all of the generators in one division of the complex organ herein described, by multiplying the connections between the individual generators and selected ones of the resonator circuits in the bank. It will be understood that each such connection will contain its own amplitude controlling impedance. Hereinafter there Awill be described a mode of using one bank of resonators for more than one division of the organ.

To obtain increased selectivity in a resonator, the Q is generally increased; but this also increases the response time of the resonator. Thus, it is necessary to control the parameters of the resonators so that the initial transients will not be too sluggish and the final transients willV not be too rever-berant. Particular resonators may have very high Qs for special effects; but in general the Q will be between and several hundred. For certain effects it may be desired to make the Q of the resonators proportional to the frequencies handled by them, in which case all frequencies will have the same transient times. On the other hand, if the Q val-ues of the resonators are made equal throughout the range, the transients of low frequency components will persist longer than the transients of high frequency components. It may be desirable to divide the resonators up into groups having Q values lying between certain limits throughout the range. This may be especially valuable where, as herein-after described, a plurality of ranks of resonators is provided, the ranks being associated either with the tones derived from different manuals, or with tones lying within certain frequency limits.

' In order to be able to pick out the 5th and 7th harmonics and others which are rather far olf tune from equally-tempered fundamentals, adjacent resonators in a single bank may be tuned fairly close together, e.g. about one-third of a semitone apart. Having rather completely covered the frequency spectrum with filters, it is possible to feed several adjacent resonators in parallel from a single source thereby achieving a faster response time than would be available from only one relatively high Q resonator. The high selectivity, slow response time feature can thereby be preserved for some tone colors while simultaneously using the same resonators for lower selectivity, faster response time depending on their input connections.

FIG. 2 also illustrates the obtaining of another effect common to organ pipes. Particularly in a Diapason voice, the second harmonic appears to speak first. In FIG. 2 resonators 46 and -56 to 62 are shown as fed with oscillati-ons from the source '32 through the switch 54. The resonator 55 for the second hanmonic is shown as provided with another switch 72 which will be operated upon the actuation of the same console key. If, however, the mechanical arrangement of the remote key switches 54 and 72 is such that the switch 72 will close (intime) slight. ly ahead of switch 54, the effect described above, namely,

the pre-sounding of the second harmonic ahead'of the fundamental and other harmonics in the particular voice, will be obtainedrsuitable tone color switches, so marked in FIG. 2, will, of course, be provided.

Another aspect which may contribute to the detiming of components in a complex tone derived from an organ using the principles outlined herein results from the fact that the' response time of a resonator is inversely proportional to its resonant frequency, fo. For a simple resonant circuit composed of resistance, inductance, and capacitance, a quantity tau (f), known as the time constant, can be shown to equal Q divided Iby 1r times fo:

Tau is the time in seconds required for the circuit response to reach 63% of its steady-state value at the initial transient and also the time required to fall to 37% 'at ,the final transient. If, for example, all the resonators in a given bank are adjusted to have the same Q value at their respective resonant frequencies, it is obvious that the higher frequency components in a complex tone will come on and go oft. at a more rapid rate than the lower frequency components at the initial and final transients, respectively. Furthermore, this feature causes the low frequency pedal tones to come on and go off much more slowly than higher frequency manual tones as is characteristic of pipe organs. A musician who has learned to make allowance for this time-lag between his manual and pedal playing technique on a pipe organ feels immediately at ease, particularly in rapid passages which yrequire good synchronization, on an electronic organ which incorporates this feature.

Harmonics of a single tone can be derived from different slightly detuned generators so as to obtain the interharmonic phase changes that occur in a single pipe tone which give it liveliness and interest inwhat is referred to as the steady state.

If a resonator is tuned to a frequency which is flat (lower) with respect to the exciting frequency, the resonator will be shock excited by an abruptly keyed-on input voltage and at first it will tend to vibrate at its own natural frequency. There will be a beat between the natural frequency of Oscillation `of the high Q resonator and the frequency of the exciting oscillation which will produce a sort of transient celeste effect which subsists only during the transient time interval determined by the resonator Q, but which is intimately associated with the style of playing of the operator of the instrument. This celeste beat-rate depends on the relative detuniug between the resonator center frequency of maximum response and the exciting generator frequency as discussed in connection with FIGS. 3, 4 and 5.

Under the circumstances just outlined, when the playing key switch is opened, the inal transient will be characterized not only by a relatively gradual decay of the tone, but also by a reversion of the resonator to its own natural frequency before the tone becomes inaudible. This will mean that during the iinal transient the tone will go at in pitch relative to that of the steady sound wave. This is a characteristic of many real wind instruments as Well as of many organ pipes. For the purpose of ob? taining this effect, the resonators may be tuned relatively at to the generators by as much as 25 or 1.5%. If different ranks of generators are provided, different relative detunings may be practiced for different voices.

As indicated above, there may desirably be, in any given bank, as many as three resonators per semi-tone in the equally tempered musical scale. In this scale, adjacent semi-tone frequencies are in a ratio of approximately 6%; hence, the indicated resonator tunings would correspond to their having peak responses every 2% along a frequency scale. Any given generator may be connected with one or more of these three resonators as to each of the partials desired to be reproduced. Thus, the system is not confined to the production of voices with true harmonics, that is, integral multiples of a fundamental frequency, but is equally applicable to the production of voices in which the partials .depart from a true harmonic relationship in the transient state. This is also true in organ pipes wherein the effective vibrating length of the air column is a function of partial frequency.

A resonator whose frequency of maximum response does not bear an integral multiple relationship to the associated input frequency can be utilized for the imitation of components in pipe organ tones which exist only in the transient state. For example, a C3 resonator may be shock-excited by an abruptly switched-on C4 signal in addition to the usual harmonic series'of resonators for C., such as C4, C5, G5, C6. Such an arrangement yields a subharmonic tone that persists for a short time only at the initial Iand final transients in vaddition to the lirst, second, third, and fourth harmonics that are steadily resonated throughout the duration of the tone. By this means, ,the chiif of a pipe organ Harmonic Flute and the tonguing transient of an orchestral flute can be simulated.

In the system of this invention tone colors can be adjusted on a per-stop, per-note, per-harmonic basis which is even more flexible than any voicing system which is used by a pipe organ manufacturer wherein voicing is limited to a perfstop, per-note basis. f

It would be possible,y on the one hand, to provide a bank of resonators for each oscillator or complex wave form in each rank of generators used in the instrument. As has already been indicated, it would be possible at the other extremeto use a single bank of resonators for the entire output of the organ, and this falls also within the scope of the invention. An intermediate type of system is, however, generally to be preferred for several reasons. In the first place, there may be desirable differences in the banks of res-onators for the voices appurtenant to different manuals, such as dilferent Q values and different relative tuning. Again, it may be preferred to provide separate expression means for different groups of voices, whether appurtenant to different manuals, or whether divided into groups in accordance with frequency. `Yet again, it is generally desirable to produce the voices of different manuals through different output systems which may differ as to kind and location. In institutional organs it is very generally desirable to locate the loud-l speaker assemblies for different manuals in dilferent parts of the church or chamber in whichthe organ is to be used.

It isbelieved that the skilled worker in the art could readily ascertain from FIG. 2 how an instrument employing a multiplicity of generator ranks but a single bank of resonators could be set up, sincesuch a system would embody essentially a repetition of the elements shown in that figure.

In FIG. 1 a system has been shown in which the tones are divided into five groups, each such group having its own resonator bank. In order to be able to control the volume of the Swell, Choir, Great, Echo, Pedal divisions independently of one another, a separate bankof resonators for each division will be required unless special cirouits are used as will now lbe described. Such separate control permits separate radiation or reproduction, so that spatial effects between divisions become possible. In the exemplary organ, the Great Manual output and the higher frequencies of the Pedal clavier are joined and handled together. Although not shown, it would be possible to provide a separate expressionvpedal for this combined output; but it is preferred to have these divisions independent of expression means corresponding to unenclosed divisions in pipe organs. A block in FIG. 1 designated by the index numeral 73, which is intended t=o represent a matrix of level adjusting impedances such as resistors (corresponding to 53 and 63 tok 70 of FIG. 2) for the resonators is shown as divided into Common, Swell, Great-Pedal, Choir and Echo divisi-ons. It will be noted that connections 74, 75, 76, 77 and 78 are diagrammatically indicated as going from all of the divisions of the spreader terminalmember 31 to the Common rank of level adjusting resistors. Connections 74, 76 and 77.are shown as containing volume control means 79, 80 and 81, about which more will be said later. The various connections 74 to 78 should be considered as carrying voltages which will `be utilized as the low frequency components of the -outputs of the Swell, Great, Choir, and Echo manuals and the Pedal clavier. Each of these connections in the exemplary embodiment is a multi-conductor cable having 608 Iwires. The high frequency outputs of the organ divisions are connected by connectors 82 to 86 inclusive to the divisions of the resistor matrices 73 marked respectively Swell, Great-Pedal, Choir, and Echo. It may be noted that these are connectors which ultimately provide the higher frequency outputs of the various organ divisions; and that each is a multi-lead cable containing 6,717

wires.

v An assembly of resonator banks is indicated generally at 87; and it comprises resonator banks 88 to 92 inclusive. The resonator bank 88 has connection as shown with the Common group of the level adjusting resistors assembly 73, and by observing the diagram toward the right, it will be seen that the output of the resonator bank 88 goes to a c ommon resonator mixing bank, common preampliiiers, and a common power amplifier and loudspeaker or speakers. The primary reason for organizing the lower frequencies into a separate group designated Cornmon in FlG. 1 is that the lower frequencies may be reproduced at substantially any point in the church or chamber inwhich the organ is to be used with out audible localization difference. It will |be remembered that the lower frequencies in a pipe organ are generally produced by large pipes located in the open (as distinguished from a sound enclosure with expression shutters) and are frequently used for decoraitve purposes. Three resonators per semi-tone are not needed for the low frequency resonator bank 8S because the fifth and seventh harmonics, for example, corresponding t-o the lowest note, C0, in this instrument lie .above the frequency range of bank 88. Banks 89, 90, 91 and 92 may have three resonators per semi-tone.

The resonator bank 89 is allocated to the Swell division voices and is designed to handle oscillations having frequencies extending from C4 (Middle C) to C10. In the exemplary embodiment there will be a total of 6,717 connections between the Swell manual group of level adjusting resistors to the resonators of the bank 89; and the output of the resonator bank 89 will be organized into 179 dierent leads. Y

Similarly, the index numeral 90 indicates a full-scale resonator bank for the Great-Pedal combination; the index numeral 91 indicates a full-scale resonator bank for the Choir manual; and the index numeral 92 indicates a fullscale resonator bank appurtenant to the Echo manual. Each of these last mentioned resonator banks has output leads numbering 179 in the exemplary embodiment.

It will be understood from the previous description of FIG. 2 that the outputs of the generators are keyed by the remote key switches in the assembly 29 and by the remote tone color switches in the assembly 30 into leads which establish connections to individual resonators of the banks 88 to 92 (there being in most instances a plurality of connections between the output of any given generator and a plurality of resonators), the specific voices being determined by resistors located in the matrix assembly 73. One reason for the provision of an assembly of these resistors in a single general location, as at 73, is that specific changes in voices are facilitated. The level adjusting resistors for the various harmonics appurtenant to any particular voice may be organized after the manner of printed circuitry with resistive coatings sprayed or otherwise imposed on insulative bases to which connections are made as, for example, by spring clips. The insulative bases containing the resistive coatings are readily replaceable by others; and if the person playing the organ of this invention iinds either that he is dissatisfied with one or more particular voices, or that one or more particular voices are not necessary for his purposes, the substitution of other printed circuitry elements in the matrix assembly 73 can be used either to change the specific harmonic content of certain voices, or to provide different voices as the case may be. This is an additional aspect .of fiexibility in the system of this invention.

The numeral 93 in FIG. 1 indicates an assembly of groups of mixers for the outputs of the several generator ranks described above. The mixers may be linear mixers of the general type indicated at 45 in FIG. 2. The outputs from the 8l leads 94 of the resonator bank 88 are combined in the Common mixer group 95 so that it need be connected by one lead only, 96, to a Common preamplifier 97 of the assembly 98. This is in turn connected by a lead 99 to a power amplifier and one or more loudspeakers diagrammatically indicated at 100. In a similar manner the outputs in the 179 leads 101 of the resonator bank 89 are mixed in the Swell manual mixing group 102. so that the combined outputs may be connected by a single lead 103 to a Swell manual preamplifier 104. Between the Swell manual preamplifier 104 and the Swell manual output system 105 there is shown a volume control or expression device 106. This expression device, which may comprise a potentiometer or similar means, is operated by the Swell manual expression shoe in the console 14. Expression devices 107 and 108 have also been shown for the Choir and Echo organs, the dashed line 109 indicating their mechanical connection with expression shoes 26 and 27 in the console. Expression means may 'be provided for the Common and Great-Pedal outputs if desired; but this is not ordinarily done in organs of the American Classic type.

It may be noted that lower frequency components of the outputs of the several manual organ divisions are sent through the so-called Common channel, and since this is the case, it will obviously be desirable to lcontrol the amplitude or expression of these lower frequency components along with the higher frequency components of the outputs of these several manual organ divisions. This may be accomplished by means of a Thyrite volume control means which has been numbered 79, 80 and 81. Thyrite is a trade name for a silicon carbide substance which varies its resistance in accordance with a D.C. voltage bias imposed on it. The Thyrite devices are quite small and relatively inexpensive. ln each of the combinations 79 to 81 there will be in the exemplary embodiment, 324 of the Thyrite devices. Means are provided in connection with the expression shoes 25, 26 and 27 to vary a D.C. voltage bias on these resistors so that the volume of the lower frequency components of the organ divisions (which are not otherwise provided with expression controlling means) may be varied with the higher frequency outputs.

The more general references previously made to key switches and stop switches will now be elaborated in connection with FIG. 6. When a key 132 in the console is depressed, a direct contact switch 133 is closed, sending direct current from a source 134 through a cable 135 to the coil of an electromagnetically-operated relay 136 located in the remote cabinet. Thus the remote key switch 137 closes a path from a generator source 138, also located in the remote cabinet, to a contact of the remote stop switch 139. If the stop tab 140 in the lconsole has been actuated, the direct contact stop switch 141 permits direct current from the source 134 to pass through a cable 142 which may if `desired be combined with cable 135. Thus a signal from the lgenerator 138 can pass through matrix or level adjusting resistor 144 to resonator 143 and to an output system 145. It should be observed that the signal switches 137 and 139 are preferably both of the two-position type whose movable contact poles are normally grounded when in the off position. This arrangement prevents signal leak-through via stray capacitance paths between the switch input and output circuits. Control of volume may be provided by a variable impedance 146, actuated by the Swell shoe 147 in the console.

The practice of the principles of this invention does not preclude the obtaining of additional Voices by ordinary formant filter means should this be desired. The skilled worker in the art will understand that additional connections may be made to individual generators in the various generator ranks, and that the generator outputs passing through these connections may be keyed by additional remote key switches, collected if desired into individual headers, and that stop-controlled formant filter means may be used in connection therewith for any voices for which additional resonator banks are not found to be necessary or desired from an economic viewpoint. FIG. l, as a matter of fact, shows at a 32-lead signal cable connecting the pedal output of the spreader terminal 31 to the Echo division of the resonator mixing bank 93. The outputs of the leads of the cable 110 are combined in an Echo pedal decoupling linear mixer indicated at 111; and the single output line of this mixer passes to the Echo division output system through a conventional, low-pass RC Bourdon 16 ft. filter indicated at 112 whose output may be controlled by a stop tab switch 113 which is physically located in the console. This is illustrative merely of an instance in which a voice may be obtained by simple formant filter means in a system otherwise as described herein.

Modifications may be made in the invention without departing from the spirit of it. The invention having been described in an exemplary embodiment, what is claimed as new and desired to be secured by Letters Patent is:

1. In an electrical musical instrument system, a source of continuous electrical oscillations corresponding in fundamental frequency to a n-ote of the musical scale and hav ing a substantial partial content, a plurality of electrical resonators of sufficiently high Q to have build-up and decay times comparable to those of partials in an organ pipe of com-parble fundamental frequency, said resonators having resonant frequencies respectively corresponding approximately to the partials of said oscillations, switching means operatively associating said source with at least certain of said resonators whereby to excite each at a frequency related to its resonant frequency, and a plurality of means operatively associated with said resonators respectively for controlling the amplitudes of the outputs thereof whereby to derive from said source via said resonators, electrical oscillations of a desired partial content and a tone envelope characterized by finite build-up and decay times.

2. The structure claimed in claim 1 in which the Q value of the resonators varies with frequency.

3. The structure claimed in claim 1 wherein the Q values of said resonators are substantially constant throughout the range :of the instrument.

4. The structure claimed in claim 1 wherein said switching means are make-and-break switching means.

5. The srtucture claimed in claim 4 including a noise generator and means for feeding the output of said noise generator to said electrical resonators.

6. The structure claimed in claim 5 wherein certain of said resonators are detuned from the frequencies of said partials so that sai-d resonators are caused to operate under continuous excitation at frequencies slightly different from their natural frequencies but, in the initial transient state to operate also at their natural frequencies momentarily and when the said signal is cut off therefrom, said resonators will revert to their natural frequencies and provide an effect of a slight detuning of pitch in a tone derived from said oscillations at the final transient.

7. In an electrical musical instrument a rank of generators of oscillations corresponding in fundamental frequency to the notes of a musical scale, said oscillations having a substantial partial content, electrical resonators 13 of sufficiently high Q to have a build-up and decay time Icomparable to that of organ pipes, said resonators having resonant frequencies respectively corresponding approximately to the partials of the oscillations produced by said generators, key controlled switching means for deriving oscillations from said generators in accordance with the requirements of a musical composition, stop controlled switching means for connecting the oscillations so derived with various ones of the resonators in said bank which resonators correspond approximately to at least selected ones of the partials of the derived oscillations, and a plurality of means operatively associated with the connections respectively from said stop controlled switches to said resonators for controlling the amplitudes of the outputs of said resonators, and means for combining the outputs of said resonators whereby to derive electrical oscillations from said generators via said resonators having pre-selected components of said partials. f

I8. The structure claimed in claim 7 wherein the Q values of said resonators vary with frequency.

9. The structure claimed in claim 7 wherein the Q values of said resonators are substantially constant throughout the range of the instrument.

10. The structure claimed in claim 7 wherein said key controlled switches and said stop controlled switches are make-and-break switching means.

11. The structure claimed in claim 10' wherein a plurality of key controlled switches is provided for at least certain ones of said generators, together with a corresponding number of stop controlled switches, whereby the oscillations derived from said generators may be sent through dilferent ones of said resonators with additional means for controlling the outputs of said resonators, whereby different voices may be derived from the same generators.

12. The structure claimed in claim 11 including a noise generator and means for feeding the output of said noise generator to said electrical resonators along with the said derived oscillations.

13. The structure claimed in claim 11 wherein certain of said resonators at least are detuned from the frequencies of the partials of said derived oscillations so that said resonators are caused to operate under conditions of continuous excitation at frequencies slighlty different from their natural frequencies but, when the said derived oscillations are cut oi therefrom, the said resonators will revert to their natural frequencies and provide an effect of slight detuning in pitch in the tone during the said decay time.

14. In an electrical musical instrument system, a source of electrical signals corresponding in fundamental frequency -to a note of the musical scale and having 4a sub'- stantial partial content, a plurality of electrical resonators of sutliciently high Q to have a build-up and decay time comparable to that of an organ pipe of comparable fundamental frequency, sa-id resonators having resonant frequencies respectively corresponding approximately to the partials of said oscillations, switching means operatively associating said source with at least certain of said resonators whereby to excite each at a` frequency related to its resonant frequency, and a plurality of means operatively associated with said resonators respectively for controlling the amplitudes of the outputs thereof whereby to derive from said source via said resonators, electrical oscillations of a desired patrial content and a tone envelope characterized by a iinite build-up and decay time, the said switching means comprising a plurality of key controlled switches for connecting said source to selected different resonators, said key switches being slightly de-timed as respects each other whereby to cause at least one partial to occur before other partials in the output of said resonators.

15. In an electrical musical instrument ranks of generators of oscillations corresponding in fundamental frequency to the notes of a musical scale, said oscillations having a substantial partial content, electrical resonators of suiciently high Q to have a build-up and decay time comparable to that of organ pipes, said resonators having resonant frequencies respectively corresponding approximately to the partials of the oscillations produced by said generators, key controlled switching means for derivingvoscillations from said generators in accordance with the requirements of a musical composition, stop controlled switching means for connecting the oscillations so derived with various ones of the resonators, which resonators correspond approximately to at least selected ones of the partials of the derived oscillations, and means operatively associated with the connections from said stop controlled switches to said resonators respectively for controlling the amplitudes of the outputs of said resonators and means for combining the outputs of Certain at least of said resonators whereby to derive oscillations from said generators having pre-selected components of said partials, certain at least of said ranks of generators being slightly detuned as respects each other to provide an ensemble etfect.

16. The structure claimed in claim 15 in which certain of said ranks of generators are detuned as respects other ranks by a greater amount so as to provide a celeste effect.

17. The structure claimed in claim 16 wherein said key controlled switches and' said stop controlled switches are electromagnetically controlled multi-contact switches, said electrical musical instrument including a console, and said switches together with said ranks of generators and said resonators being located at a point remote from said console.

18. The structure claimed in claim 17 wherein said pluf rality of means in the connections between said stop controlled switches and said resonators for controlling the amplitudes of the outputs of said `resonators include impedance means on insertable and removable circuit elements whereby the voices of said organ may be changed.

19. In an electrical musical instrument system a console having playing keys arranged in several manuals and a pedal clavier, stop means, and a plurality of expression pedals, said system including at a point remote from said console a cabinet containing la plurality of ranks of generators, a plurality of key-controlled switches, a plurality of multi-contact stop-controlled switches, and a plurality of banks of resonators having frequencies respectively corresponding approximately to the partials of complex oscillations produced by the generators in said ranks, switches operated by the playing keys in said console `and having operative circuit connections with said remote key-controlled switches, switches associated with the stops in said console and having circuit connections with said remote stop-controlled switches, and connections through said remote key-controlled switches and said remote stop-controlled switches for each generator in said ranks to various ones and combinations of resonators in said resonator banks, said connections including means for controlling the relative outputs of the individual resonators to which said connections are made, a separate output system for each of said banks of resonators, certain at least of said output systems including volume control means having connection with the expression pedals in said console.

20. An electronic musical instrument having an electrical resonator of predetermined natural frequency and of sutiicie'ntly high Q to have build-up and decay times comparable to a corresponding organ pipe partial of nearly the same frequency as said natural frequency, an electroacoustic output system connected thereto, and means connected to said resonator for shocking said resonator into a transient oscillatory state at its resonant frequency, whereby to simulate a chif component of an organ pipe.

21. An electronic musical instrument having a continuous tone wave generator, keying means in connection therewith `and controlling the output thereof, at least one electrical resonator operatively associated with said generator by said keying means and having a relatively long and .audibly-sensible self-oscillatory time constant for a resonant frequency musically related to the frequency of said tone wave generator, said self-oscillatory time constant being selected to effect simulation by Said electrical resonator of the build up and decay of a pipe organ partial at the frequency of said resonator lby virtue of the self-oscillatory time constant of a pipe of the pipe organ, an electroacoustic output system connected to said resonator.

22. An electronic musical instrument having a source of driving signal having at least a fundamental frequency component, a resonant circuit having a relatively long and audibly-sensible time constant approximately that of an organ pipe of the frequency of said resonant circuit and a natural audible resonant frequency displayed from said fundamental frequency component, an acoustic transducer in connection with said resonant circuit, and means in connection with said source and said resonant circuit for shock exciting the latter into self oscillation at said natural resonant frequency and for concurrently driving said transducer in response to said driving signal.

23. The combination according to claim 22, wherein said driving signal comprises a complex spectrum `and wherein said natural frequency of said resonant circuit is at least approximately equal to a partial of said spectrurn.

24. An electronic musical instrument having a source of driving signal having at least a fundamental frequency component, a resonant circuit having a relatively long and audibly-sensible time constant and Ia natural audible resonant frequency different from said fundamental frequency component, an acoustic transducer in connection with said resonant circuit, and means in connection with said source yand said resonant circuit for shock exciting the latter into oscillation at said natural o audible resonant frequency different from said fundamental frequency component, an acoustic transducer in connection with said resonant circuit, and means in connection with said source and said resonant circuit for shock exciting the latter into oscillation at said natural resonant frequency and for concurrently driving said transducer in response to said driving signal, wherein said natural resonant frequency is at least approximately a sub-harmonic of said fundamental frequency component.

References Cited y UNITED STATES PATENTS 2,681,585v

6/1954 Hanert 84L24 2,939,359 6/1960 Markowitz 84-1.24 2,989,886 6/1961 Markowitz SLI-1.19 2,233,948 3/1941 Kock 84-1.21 X 2,963,933 12/1960A Bereskin 84-1.1l X 3,098,407 7/1963 Brand 84-1.11

ARTHUR GAUSS, Primary Examiner. LAWRENCE V. EFNER, Examiner.

J. W. YOUNG, I. BUSCH, R. H. PLOTKIN,

Assistant Examiners. 

1. IN AN ELECTRICAL MUSICAL INSTRUMENT SYSTEM, A SOURCE OF CONTINUOUS ELECTRICAL OSCILLATIONS CORRESPONDING IN FUNDAMENTAL FREQUENCY TO A NOTE OF THE MUSICAL SCALE AND HAVING A SUBSTANTIAL PARTIAL CONTENT, A PLURALITY OF ELECTRICAL RESONATORS OF SUFFICIENTLY HIGH Q TO HAVE BUILD-UP AND DECAY TIMES COMPARABLE TO THOSE OF PARTIALS IN AN ORGAN PIPE OF COMPARABLE FUNDAMENTAL FREQUENCY, SAID RESONATORS HAVING RESONANT FREQUENCIES RESPECTIVELY CORRESPONDING APPROXIMATELY TO THE PARTIALS OF SAID OSCILLATIONS, SWITCHING MEANS OPERATIVELY ASSOCIATING SAID SOURCE WITH AT LEAST CERTAIN OF SAID RESONATORS WHEREBY TO EXCITE EACH AT A FREQUENCY RELATED TO ITS RESONANT FREQUENCY, AND A PLURALITY OF MEANS OPERATIVELY ASSOCIATED WITH SAID RESONATORS RESPECTIVELY FOR CONTROLLING THE AMPLITUDES OF THE OUTPUTS THEREOF WHEREBY 